scsi: qedi: Cleanup local str variable

Signed-off-by: Nilesh Javali <nilesh.javali@cavium.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Acked-by: Chris Leech <cleech@redhat.com>
Acked-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>